This study uses data from the longitudinal Panel Study of Income Dynamics data and its Transition to Adulthood (TA) Study (2005–2017), in conjunction with decades of neighborhood-level data from the U.S. decennial census and American Community Survey, to examine the relationship between individuals’ neighborhood poverty exposure trajectories in childhood and the likelihood of obesity in emerging adulthood. Latent growth mixture models reveal that exposure to neighborhood poverty differs considerably for white and nonwhite individuals over their childhood life course. Durable exposure to neighborhood poverty confers greater subsequent obesity risks in emerging adulthood than transitory experiences of neighborhood poverty. Racial differences in the changing and persistent trajectories of neighborhood poverty help explain part of the racial differences in obesity risks. Among nonwhites, and compared to consistent nonpoor neighborhood conditions, both durable and transitory neighborhood poverty exposures are significantly associated with higher obesity risks. This study suggests that a theoretical framework that integrates key elements of the life-course perspective is helpful to uncover the individual and structural pathways through which neighborhood histories in poverty shape population health in general.